I think the main problem is that CX is not encouraging online booking (apart from the double miles from using CX AMEX). I have once called SQ in HKG and have been told that they only sell full fare tickets over the phone. For most discounted fares they encourage you to book online. BA also imposes an offline booking fee of HKD200 per person. It's even worse if you call either of these airlines' offices in London - they charge you even for calling them (by using 0845 and 0870 numbers, which costs about HKD1 per minute)!